@Ma**
, to save yourself the money you have been paying an agent to "push paper" (get your extensions of stay) just stop by the immigration office and get the hand out that lists the documentation required.
Also in Chiang Mai you can apply for an extension when you have 45 days or less left on your current one. There is NO need to wait until it is almost expiring because they ADD the new year's extension to the expiration date of the old one so you don't lose time by going early.